Photos

BEIJING, CHINA - MARCH 29: (CHINA OUT) Workers lay the athletics track at National Stadium (also known as "Bird Nest") on March 29, 2015 in Beijing, China. The International Association of Athletics Federations (IAAF) World Champions Beijing 2015 will be held from August 22 to August 30. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)